Parameterization for fading compensation

Abstract

Techniques and tools for performing fading compensation in video processing applications are described. For example, during encoding, a video encoder performs fading compensation using fading parameters comprising a scaling parameter and a shifting parameter on one or more reference images. During decoding, a video decoder performs corresponding fading compensation on the one or more reference images.

1. A method for encoding video information using a computing device that implements a video encoder, the method comprising, during encoding:
 with the computing device that implements the video encoder:
 for a current video frame having plural reference video frames, signaling a fading compensation flag at a first syntax level in a video bitstream; and 
 when the fading compensation flag at the first syntax level indicates fading compensation is activated for the current video frame having plural reference video frames, signaling plural fading parameters at a second syntax level lower than the first syntax level in the video bitstream, wherein the plural fading parameters are for fading compensation for at least part of the current video frame having plural reference video frames, and wherein the fading compensation comprises adjusting plural pixel values in the plural reference video frames based at least in part on the plural fading parameters. 
 
 
     
     
       2. The method of  claim 1  wherein the plural pixel values in the plural reference video frames comprise luminance values and chrominance values. 
     
     
       3. The method of  claim 1  wherein the plural pixel values include all pixel values in the plural reference video frames. 
     
     
       4. The method of  claim 1  wherein the first syntax level is frame level and wherein the second syntax level is a portion of a frame. 
     
     
       5. The method of  claim 1  wherein the plural fading parameters comprise at least one weighting parameter and at least one offset parameter. 
     
     
       6. The method of  claim 1  wherein the plural fading parameters include one or more fading parameters for adjusting luminance values and one or more different fading parameters for adjusting chrominance values. 
     
     
       7. A computer-readable medium, not consisting of a signal, storing computer-executable instructions for causing a computer system programmed thereby to perform the method of  claim 1 . 
     
     
       8. A method for decoding video information using a computing device that implements a video decoder, the method comprising, during decoding:
 with the computing device that implements the video decoder:
 for a current video frame having plural reference video frames:
 receiving and processing a fading compensation flag at a first syntax level in a video bitstream; and 
 when the fading compensation flag at the first syntax level indicates fading compensation is activated for the current video frame having plural reference video frames, receiving and processing plural fading parameters at a second syntax level lower than the first syntax level in the video bitstream, wherein the plural fading parameters are for fading compensation for at least part of the current video frame, and wherein the fading compensation comprises adjusting plural pixel values in the plural reference video frames based at least in part on the plural fading parameters. 
 
 
 
     
     
       9. The method of  claim 8  wherein the plural pixel values in the plural reference video frames comprise luminance values and chrominance values. 
     
     
       10. The method of  claim 8  wherein the plural pixel values include all pixel values in the plural reference video frames. 
     
     
       11. The method of  claim 8  wherein the first syntax level is frame level and wherein the second syntax level is a portion of a frame. 
     
     
       12. The method of  claim 8  wherein the plural fading parameters comprise at least one weighting parameter and at least one offset parameter. 
     
     
       13. The method of  claim 8  wherein the plural fading parameters include one or more fading parameters for adjusting luminance values and one or more different fading parameters for adjusting chrominance values. 
     
     
       14. A computer-readable medium, not consisting of a signal, storing computer-executable instructions for causing a computer system programmed thereby to perform a method for decoding video, the method comprising:
 for a current video frame having plural reference video frames:
 receiving and processing a fading compensation flag at a first syntax level in a video bitstream; and 
 when the fading compensation flag at the first syntax level indicates fading compensation is activated for the current video frame having plural reference video frames, receiving and processing plural fading parameters at a second syntax level lower than the first syntax level in the video bitstream, wherein the plural fading parameters are for fading compensation for at least part of the current video frame, and wherein the fading compensation comprises adjusting plural pixel values in the plural reference video frames based at least in part on the plural fading parameters. 
 
 
     
     
       15. The computer-readable medium of  claim 14  wherein the plural pixel values in the plural reference video frames comprise luminance values and chrominance values. 
     
     
       16. The computer-readable medium of  claim 14  wherein the plural pixel values include all pixel values in the plural reference video frames. 
     
     
       17. The computer-readable medium of  claim 14  wherein the first syntax level is frame level and wherein the second syntax level is a portion of a frame. 
     
     
       18. The computer-readable medium of  claim 14  wherein the plural fading parameters comprise at least one weighting parameter and at least one offset parameter. 
     
     
       19. The computer-readable medium of  claim 14  wherein the plural fading parameters include one or more fading parameters for adjusting luminance values and one or more different fading parameters for adjusting chrominance values. 
     
     
       20. The method of  claim 1  further comprising:
 detecting whether fading occurs in the current video frame relative to one or more of the plural reference video frames. 
 
     
     
       21. The method of  claim 20 , wherein the detecting comprises:
 computing an error measure for the current video frame relative to one or more of the plural reference video frames; and 
 comparing the error measure with a fading detection threshold. 
 
     
     
       22. The method of  claim 21  further comprising:
 before the computing the error measure, downsampling the current video frame and one or more of the plural reference video frames. 
 
     
     
       23. The method of  claim 21  wherein the error measure is absolute error sum. 
     
     
       24. The method of  claim 1  wherein the computing device includes a processing unit, memory, a display, and a wireless communication connection. 
     
     
       25. The method of  claim 8  wherein the computing device includes a processing unit, memory, a display, and a wireless communication connection.